Longitudinal actuating apparatus



Sept., 21, 1948. R. c. MARHoLz LONGITUDINAL ACTUATING APPARATUS Filed April 28, 1945 JKM/wg, m'aa www )5IN V EN TOR.

www w @w w Patented Sept. 21, 1948 UNITED "STATES PATENT oFFflCfE' Richard JC... yMaiholn Cl'licagm-n:111.1,`v I:assigner to Belmont'RadioDorperation, @Chicag0,;Ill.,facor poration offlllinos s claims. (ci. #4a-441;)

tsf rather-looselyin the guide slotandfthere iesults "a :certain i amount of back-lashy or llost-` motion in the mechanism; Ithatiis avcertain amount otirotation of the actuating Amechanism takes placevf'in reversing its direction of Zrotation 1before the-motion of the driven member-is-lreversedl.

This back-lashfis troublesome in many installationspsucli 1-as in the'adjustment` of 4a transmission line tuner comprising i stationary and'fmovable telescoping -jcylin'drical conductors.

ltwis` an object -of thecinvention;-thereforey'to provide 'a newA and Ainfiprovedlongitudinalfactuating'apparatus `which-iovercomesi the abovementioned disadvantages v-oi the arrangements of fthe i prior art* f and `specifically substantially eliminates back-lash between the actuating tand drivenmechanism.

Inaccordance with the invention .ap paratus for -longitudinally actuating `a driven member comprises va rotatable 4actuating means, -a'leadscrewfdriven by the actuating means, -a longitudinal guide adjacent the lead-screw 'an-d having parallel opposed faces, and a driven member having 'a follower engaging the lead-screw. The Adriven member also comprises a mechanism including a'pair of relatively movablelarms engaging the guide and meansffor biasing the arms into engagement with the opposed faces of the guidesubstantially to eliminate back1lash"be tween the actuating means and'the'driven-member.

Ina specific embodiment of the invention, rapparatusffor adjusting a transmission-line `tuner comprising stationary and movable telescop-ing cylindrical conductors comprises a `rotatable actuating means, `a lead-screw driven `by 4'the` actun ating means. and `concentric with the conductors, and a `longitudinal cylindrical slotted 'guidecom centric with :thellead-screw and adaptedA to serve as` the stationaryfconductor of:theliney Thefapff paratus :also :includes pa :driven :member for conf nection 'tonthe movableiconductor :of `the `line "and having. :a iolloweraengaging the slead-fscrevv,tanti a mechanism including.: a @pair llof` :relatively finov able armsengaging the slotzofith-elguide; "The .apparatus also includes :meansaforbiasing thearms apart and "finto engagement: r with n :the #opposed 'faces ofxthe @slot substantiallytoV eliminate :back- IaSh. i t` For a .better understanding offfthe inventiony together s with other. and :further `obj ectsl there*- of,A reference :is had ito: the. followingI description taken Aiin #connection :with: ithe accompanying drawings. while its iscopesawill Ibe :pointed foutf-in the appended claims.y i

Referring .new the drawing, 1Fig'..f1 :is a longh tudi-nal .sectional fvievv ,'of aan` actuating appar r-atus embodying` @the invention and Iinc'orpcrat ed in r an:` adjustableiftransmissionlline tunerr with an associated i Yindicating 'and fzrotationelimiting apparatusesh'own :schematica-Hy; 'Fig f2 nis a "crosssectional :detail and Fig f3 .fa longitudinali sectionalfview ofithezfifo'llower Vdevice fof the a1cpa-4 ra'tus` oifFig.fr1;-while Fig. si is -a cross-:sectional detail oi'.tlientelescoping transmission-line con ductorsmfithe apparatusaofi'ig. A11.` .Referringy now lto IFig. 1 fof the drawing; @there is represented @apparatus :embodying f the. zinvenn ti'om-tionieiecting "longitudinal smevement iof a` driven imemberr fofr example", apparatus fori ad .lusting a ftransmissiomline tunerfcomprising sta-- tionary .and :movabletelescoping-:cylindrical conn ductors` lill@and2l-1L:r respective'lyw The cylindri" calV conductor fl l'is :secured in Ia {cylindrical-f recessll2afin van wend-iframe l2 by any suitable 1 meansgsuchLasfsetfscrews 13. Theiconductorfli iss providedvfwith a :series of Y--resilient contact :iingl gersnorV brushes 10d which-make electricalfcontact riwithlfithe lte'lesccping 4conducto-r`=fl I; As ill li stratedz the Itransirt-ssion-line ltuner is'of the concentricdirie ltype :and fincludes i -an .outer 'iconvcentric f cylindrlcalf iconductor 21M* secured- -to Wa cylindrical fhub '==If2b ofthe frame member il? Pby suitable means such fas screws' 'i5'. i To' `th'ere` mote endo'f theconductor"lil` issecureda cap i6 of ra diameterslightly Aless than the *inner diameterof theffconductor I4 fand lprovided with reeA silient contactr'ngers'or -`brushes Hla engaging theconductorlill. The'outerend of the conduc-i tor lz'll isl preferably closed Aby fan integral orV assembledplate' il 4m i' ."The s'apparatus :also `includes =rotatablel-lactu atingcmeainsifor driving the-cylindrical conduc: tor,I lflrzpzforziexampleca zmamuetlly` operable knob .H secured tto :a :driringl shaft; .48 which; lin Sturn'. swconncctedf-to:.fdrireua :rotatable zlead-iscrewcts as by means of a key 20 engaging an extension Ia of shaft I8 seated in a recess I9a at the end of the lead-screw I9. The shaft I8 and leadscrew I9 are mounted concentrically with the conductors I0, II and I4 and are supported in suitable bearings, one of which is shown in the form of an anti-friction bearingl 20a supported in the frame I2.'` Y j' Y The apparatus also includes la longitudinal guide adjacent the lead-screw and having opposed parallel faces. For example, the stationary conductor I of the transmissionv line may be provided with a guide slot IDb and serve as the guide for the apparatus, The apparatus alsof includes a driven member 2| connected or securedl to the movable conductor II of the transmission 4 from the slide 34 and a portion of the frame member 36 is effective to bias the roller 34 into engagement with the cam 32. The frame 36 also constitutes additional guide means for the slide 34 lto confine it to rectilinear motion. If desired, a Vernier indicating means or scale plate 3I may be mounted on the driven shaft I8 and a coarse indicating l means or scale drum "38A may b mounted on the auxiliary cam shaft 2'I. It is believed that the operation of the apparatus of the invention will be apparent from the foregoing. description. In brief, adjustment of the knob I1 is effective to rotate the shaft I8 and the lead-screw' I9 which acts on the follower line. As shown more clearly in Fig. 2,the mem` ber 2|' may comprise a cylindrical sleeve ,rotat-V ably mounted on the lead-screw I9 and" secured to the conductor II by means of a pin 2'2 provided With a proje-ction 22a; engaging-and closely fitting the thread of the lead-screw yI9 and constituting a follower therefor.

The driven member 2I of the apparatus also comprises a mechanism including a pair of relatively movable arms engaging the opposed faces of the guide, preferably one-of the arms being fixed and one pivoted to the driven member. For example, as shown more clearly in Figs. 2 and 3, the-mechanism comprises a pair of concentric notched rings 23 and 24 mounted on a cylindrical hub 2Iaof the member 2I, the ring 23 being fixedly mounted on the member 2| by any suitable means such as a pair of `cap screws 25. The other ring 24 is relatively-rotatably mounted with respectto the ring 23 as by means of arcuate slots 24a engaging enlarged, unthreaded Shanks 425a, of the screws 25. The rings 23 and24 have radially extending arms 23h and 24h, respectively, extending into the guide slot I 3band of a width somewhat less y'than the width of the slot. The apparatus also includes means for biasing the arms `23h and 24h apart and into engagement with opposed faces of the guide slot` Ill'b. This biasing means may be in the form of a compression spring 26 engaging opposed end walls of registering notches of the rings 23 and 24.

The driving apparatus of the invention mayv be actuated by any suitable means but there is illustrated schematically, by Way of example, an apparatus for limiting the rotation of the shaft I8 to a predetermined number of revolutions, this a-pparatus, per se, forming the subject matter` of applicants copending application Serial No. 590,892, filed April 28, 1945, entitled "Shaft rotationlimiting apparatus. In brief, this driving apparatus comprises an auxiliary -cam shaft 2'I and a reduction drive means between the shafts I8 and 21 comprising a worm 28 on the shaft I8 engaging a worm wheel 29 on an intermediate shaft 30 which, in turn, drives the shaft 2'I through the spur gearing 3Ia, 3Ib. A cam` 32 having a depressed portion 32a is mounted on the shaft '21 and there is provided mechanism actuated by the cam 32 for limiting the rotational movement of the driven shaft I 8. l This mechanism-may comprise a member rotatable with the driven shaft I8, for examplean arm 33 mounted thereon, and a reciprocating slide 34 movable into engagement with the arm 33 under the control of the cam 32. For example, the slide 34 includes a roll- 1 22a of the driven member 2| to effect longitudinal movement of the member 2| and its associated cylindrical conductor II and end cap I6.

In order to prevent excessive friction and minimizefbinding in the guide slot IDb, the arms 23h and 24h are of a width considerably less than the width of the slot Ib, while the spring 26 is elective to produce` relative rotation of the notched rings 23 and'24 so that the arms 23h and 24h are biased into engagement with opposed faces of the slot I0b. This arrangement ensures that the stationary arm 23h-is always in a fixed angular position relative to the cylindrical conductor I0b and substantially eliminates back-lash .between the actuating knob I'I and the shaft I8` and the driven member 2l and its associated conductorl I This elimination of back-lash is particularlyeffective upon reversal of the direction of v,adjustment of the knob I'I, which would otherwise cause a portionof the driven member 2 I to engage rst one side-and then the other side of the slot Ib.

By virtue of the contact between the resilient fingers Illa of the cylindrical conductor I0 `and the-cylindrical conductor II and of the electrical contact between the resilient lingers IBa of -the cap I6 and the outer cylindrical conductorf, there is provided a concentric transmission line, the effective electrical length of which, and thus its tuning, may be adjusted by longitudinal adjustment of the conductor II and its associated cap I 6. In the particular example illustrated, the

- concentric line is short-circuited at its remote end but it will be readily understood that it,v may be modified by conventional methods to provide-.an open-circuit transmission line of adjustable length. f l

The rotation limiting apparatus described is effective to limit the number of revolutions of the shaft I8 to a predetermined number. corresponding to the range of longitudinal adjustment ofthe cylindrical conductor I.I. The number of revolutions of the shaft I8 is somewhat less thanthe product of the gear ratiosbetween the worm- 28 and the worm wheel 29 and that ybetween .the gears 3 la, 3 lb. Thus, assuming lthat the element-s are `in the relative positions shown in Fig. l, it is seen that further adjustment of ytheknofb Ilfin-a counterclockwise direction, which would tend to drive the cap i6 lbeyond the limits of its normal travel, .is elfective to allow the cam roller 34a to fall vinto the depressed portion 32a yof fthe cam 32 and .to permit the :slide 34--to move under theiniluence of the spring 35 so that the portion Ythere- -of projecting through; Ithe frame 36 extend-s intO. the path of movement of the arm 33, as illustrated in thek dotted-'line position, preventing further rot-ation of the knob I'I and the4 shaft I8. Conversely, upon rotation of the knob II and shaft I8 in a clockwise direction, the cam 32` and-cam roller 34a maintain the slide 34 out of engage.- ment with .the arm 33 for a number bf revolutions of `the shaft I8 equal to the ,product of the gear ratio of the worm 28 and worm wheel 29 and th-at of lthe gears 3m, 3lb multiplied by the fraction which the raised portion of lthe cam 32 is of 'a compl-ete circle. The gear ratio-s are obviously so selected that lthe cam roller 34a again falls into the slot 32a after a number lof revolu- Itions of the shaft i8 corresponding to t'he adjustment of the cylindrical conductor ll to its extreme telescoped position within the conductor I0. After such adjustment, the cam roller 34a again falls into the depression 32a of the cam 32 So that the slide 34 engages the arm 33 and prevents further clockwise rotation of the knob I'l and t'he shaft I8.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be apparen-t to those slrilled in the art that various changes and modificaltions may be made therein without departing from Athe spirit or scope of t-he invention.

What is claimed as new is:

1. Apparatus for longitudinally actu-ating a driven member comprising, a rotatable actu-ating means, a lead-screw driven by said actuating n tively movable arms engaging said guide, and

means for biasing said arms into engagement with the opposed faces of said guide substantially to eliminate back-lash |between said actuating means and said ydriven member.

2. Apparatus for longi-tudinally actuating a u driven member comprising, a rotatable actuating means, a lead-screw driven by said actuating means, a longitudinal slotted guide adjacent said lead-s-crew, a driven lmember having a follower engaging said lead-screw and a mechanism including a pair of relatively movable arms engaging the slot of said guide, and means for .bia-sing said arms apart and into engagement with the opposed faces of said slot substantially to eliminate back-lash between said actuating means and said driven member.

3. Apparatus for longitudinally actuating a driven member comprising, a rotatable actuating means, a lead-screw driven by said actuating means, a longitudinal guide adjacent said leadscrew having parallel opposed faces defining a slot, a driven member having a follower engaging said lead screw and a mechanism including a fixed arm and a pivoted arm engaging said guide, and means for biasing said arms into engagement with the opposed faces of said slot substantially to eliminate back-lash between said actuating means and said driven member.

4. Apparatus for longitudinally actuating a driven member comprising, a rotatable actuating means, a lead-screw driven by said actuating means, a longitudinal guide adjacent said leadscrew having parallel opposed faces defining a slot, a driven member having a follower engaging said lead screw and a mechanism including a pair of concentric relatively rotatable notched rings each having an arm engaging said guide, and a compression spring engaging opposed end walls of the notches of said rings for biasing said arms into engagement with the opposed faces of said slot substantially to eliminate backlash between said actuating means and said driven member.

5. Apparatus for longitudinally actuating a driven member comprising, a rotatable actuating means, a lead-screw driven by said actuating means, a longitudinal guide adjacent said leadscrew having parallel opposed faces so as to define a slot, a driven member including a sleeve rotatably mounted on said lead-screw and having means engaging the thread thereof and a mechanism including a pair of arms engaging said guide, and means for biasing said arms into engagement with the opposed faces of said slot substantially to eliminate back-lash between said actuating means and said driven member.

6. Apparatus for longitudinally actuating a driven member comprising, a rotatable actuating means, a lead-screw driven by said actuating means, a longitudinal guide adjacent said lead-screw having parallel opposed faces defining a slot, a driven member including a sleeve rotatably mounted on said lead-screw and having means engaging the thread thereof and a pair of notched rings relatively rotatably mounted on said sleeve each having an arm engaging said guide, and a compression spring engaging opposed end walls of the notches of said rings for biasing said arms into engagement with the opposed faces of said slot substantially to eliminate back-lash between said actuating means and said driven member.

7. Apparatus for longitudinally actuating a driven member comprising, a rotatable actuating means, a lead-screw driven by said actuating means, a longitudinal guide adjacent said lead-screw having parallel opposed faces defining a slot, a driven member including a sleeve rotatably mounted on said lead-screw and having means engagingthe thread thereof and a pair of notched rings, one xedly mounted and the other pivotally mounted on said sleeve, each of said rings having an arm engaging said guide,

l and a compression spring engaging opposed end walls of the notches of said rings for biasing said arms into engagement with the opposed faces of said slot substantially to eliminate backlash between said actuating means and said driven member.

8. Apparatus for adjusting a transmissionline tuner comprising stationary and movable telescoping cylindrical conductors comprising, a rotatable actuating means, a lead-screw driven by said actuating means and concentric with said conductors, a longitudinal cylindrical slotted guide concentric with said lead-screw and adapted to serve as the stationary conductor of said line, a driven member for connection to the movable conductor of said line having a follower engaging said lead screw and having a mechanism including a pair of relatively movable arms engaging the slot of said guide and means for biasing said arms apart and into engagement with the opposed faces of said slot substantially to eliminate back-lash between said actuating means and said driven member.

RICHARD C. MARHOLZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,231,855 Cox July 3, 191'7 1,854,698 Burger Apr. 19, 1932 1,947,069 Thomas Feb. 13, 1934 

